[j-nsp] Internet routes in MPLS network, global table or own VRF?
plunin at senetsy.ru
Thu Jan 26 16:33:38 EST 2012
> > Because FRR uses a path from a different entry (PLP) to probably a
Ups, I meant PLR, of course.
> > exit (say, next-next-hop). When normal LSP (either SPF or CSPF
> > is a path from head-end to tail-end. Whether this happens often or rare,
> > need to care how your detours are calculated is itself a big enough
> > headache.
> That's not how FRR works at least for RSVP. It pretty much just
> re-runs cspf with something removed. So it's the same route your IGP
> would choose if said "thing" went dark. I don't have many obscure
> paths where I wouldn't want traffic to go so I can't really comment on
> your earlier idea. That being said I've never seen FRR choose a path
> worse than the path the IGP would choose. It's just preselects that
> path and pre-signals it. I'm sure there are failure scenarios though.
Seems like you confuse FRR (aka local repair) with secondary LSP path. FRR
path setup is initiated by P routers, when the primary and secondary LSP
paths are initiated by head-end PE. FRR detour only holds until IGP
recalculates a new path (doesn't much matter with or without TE), which can
(and very probably will) not even include the P router, acted as a point of
local repair after failure.
More information about the juniper-nsp